Single crystal diamond manufactured using chemical vapor deposition (assisted by plasma, hot filament, flame, etc) is harder than any other semiconductor material. The hardness of it makes it difficult to polish using standard semiconductor techniques. A combination of physical mechanical polishing processes and non contact polishing processes is required to achieve a surface condition that is acceptable for a variety semiconductor and optical applications (eg: Tunable structures, Optically Pumped Semiconductor, Laser Inner Cavity, Laser Windows, Heat Sinks, Bonding, FETs, etc. . . ).
Traditional diamond polishers are utilized using impregnated or metal bonded diamond wheels for rough bulk polishing using a high precision level for parallelism. This achieves a flat and parallel surface that is within a few microns of device ready specifications. However, these surfaces typically have numerous multi-nanometer height spikes and discontinuities which prevent optical bonding, degrade photolithographic images and may literally be higher than the thickness of active layer in a tunable structure (ie: optical diamond waveguides, hetro-structures, delta doped structures, biosensor active layers, etc.).
Plasma, reactive ion etching (RIE) and Gas-cluster ion-beam (GCIB) are non contact processing techniques used to provide smooth, flat and parallel surfaces that can be directly applied to device applications. Plasma and RIE technique provide smooth and planarized surfaces which may leave undesirable surface damage. These techniques may be used separately or in combination with one another including GCIB to provide better surfaces and specifications that could not otherwise be attained. GCIB technology offers the ability to change the nature of the surface without affecting the bulk properties. A Gas Cluster Ion Beam (GCIB) source is able to deliver highly energetic clusters of weakly-bound atoms providing extremely low damaged surfaces. The gas-cluster beam is capable of providing smoothing etching and planarization of the extreme surface of numerous semiconductors, metals, insulators, and magnetic materials.